Extended Life Coolants (ELCs) for internal combustion engines are based on Organic Acid Technology (OAT) and include an organic acid and other ingredients such as potassium hydroxide, ethylene or propylene glycols, water, etc. Recently OAT based coolants have been replacing silicate based coolants because of the longer service life of the OAT corrosion inhibitors. Unlike silicate based inhibitors, OAT inhibitors typically do not deplete over the 150,000 mile/5 year service interval. Most manufacturers emphasize the low to no maintenance feature of OAT coolants. Over the life of the coolant, the organic acids in ELCs can become depleted or compromised due to “topping off” with water or conventional (silicate based) coolant, and for optimal ELC performance and engine protection, it is important to maintain the total organic acid content of the ELC within a particular performance range. Replacing an ELC when it is still in an acceptable performance range can result in unnecessary costs, and failing to replace an ELC that is no longer within an acceptable performance range can lead to engine damage and lost productivity.
To avoid damage to engines and devices that results from contamination or dilution of an ELC, it is useful to be able to determine chemically the remaining organic acid content in the coolant to provide information on the coolant status.